Fix UnusedName warnings revealed by v0.14.1 PS release

Description of the change

Self-explanatory.

Backlinking to purescript/purescript#4071

Checklist:

[x] Added the change to the changelog's "Unreleased" section with a link to this PR and your username
[ ] Linked any existing issues or proposals that this pull request should close
[ ] Updated or added relevant documentation in the README and/or documentation directory
[ ] Added a test for the contribution (if applicable)

purescript / purescript-filterable